[llvm] 93fb1ba - [X86] LowerVectorAllEqual - don't attempt to match comparisons of float data

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2023-04-06T11:31:59+01:00
New Revision: 93fb1bac674b07134f7de59ba22d3d5acf741637

URL: https://github.com/llvm/llvm-project/commit/93fb1bac674b07134f7de59ba22d3d5acf741637
DIFF: https://github.com/llvm/llvm-project/commit/93fb1bac674b07134f7de59ba22d3d5acf741637.diff

LOG: [X86] LowerVectorAllEqual - don't attempt to match comparisons of float data

FCMP may use ISD::SETNE when nnan, we don't want to end up with cases where we mismatch signed zeros etc.

Thanks to @pengfei for the test case from D147688

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86ISelLowering.cpp
    llvm/test/CodeGen/X86/movmsk-cmp.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index eb3afd4cc151..dc07a034b189 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -24352,6 +24352,10 @@ static SDValue LowerVectorAllEqual(const SDLoc &DL, SDValue LHS, SDValue RHS,
   if (!llvm::has_single_bit<uint32_t>(VT.getSizeInBits()))
     return SDValue();
 
+  // FCMP may use ISD::SETNE when nnan - early out if we manage to get here.
+  if (VT.isFloatingPoint())
+    return SDValue();
+
   assert((CC == ISD::SETEQ || CC == ISD::SETNE) && "Unsupported ISD::CondCode");
   X86CC = (CC == ISD::SETEQ ? X86::COND_E : X86::COND_NE);
 

diff  --git a/llvm/test/CodeGen/X86/movmsk-cmp.ll b/llvm/test/CodeGen/X86/movmsk-cmp.ll
index 9e0d2a98aacb..e7f9b3639268 100644
--- a/llvm/test/CodeGen/X86/movmsk-cmp.ll
+++ b/llvm/test/CodeGen/X86/movmsk-cmp.ll
@@ -3330,6 +3330,54 @@ define i1 @allzeros_v8i64_and4(<8 x i64> %arg) {
   ret i1 %tmp3
 }
 
+; FCMP may use ISD::SETNE when nnan, don't attempt to use LowerVectorAllEqual.
+define i1 @allzeros_v8f32_nnan(<8 x float> %a0) {
+; SSE-LABEL: allzeros_v8f32_nnan:
+; SSE:       # %bb.0:
+; SSE-NEXT:    xorps %xmm2, %xmm2
+; SSE-NEXT:    cmpneqps %xmm2, %xmm1
+; SSE-NEXT:    cmpneqps %xmm2, %xmm0
+; SSE-NEXT:    packssdw %xmm1, %xmm0
+; SSE-NEXT:    pmovmskb %xmm0, %eax
+; SSE-NEXT:    testl %eax, %eax
+; SSE-NEXT:    setne %al
+; SSE-NEXT:    retq
+;
+; AVX1OR2-LABEL: allzeros_v8f32_nnan:
+; AVX1OR2:       # %bb.0:
+; AVX1OR2-NEXT:    vxorps %xmm1, %xmm1, %xmm1
+; AVX1OR2-NEXT:    vcmpneqps %ymm1, %ymm0, %ymm0
+; AVX1OR2-NEXT:    vmovmskps %ymm0, %eax
+; AVX1OR2-NEXT:    testl %eax, %eax
+; AVX1OR2-NEXT:    setne %al
+; AVX1OR2-NEXT:    vzeroupper
+; AVX1OR2-NEXT:    retq
+;
+; KNL-LABEL: allzeros_v8f32_nnan:
+; KNL:       # %bb.0:
+; KNL-NEXT:    # kill: def $ymm0 killed $ymm0 def $zmm0
+; KNL-NEXT:    vxorps %xmm1, %xmm1, %xmm1
+; KNL-NEXT:    vcmpneqps %zmm1, %zmm0, %k0
+; KNL-NEXT:    kmovw %k0, %eax
+; KNL-NEXT:    testb %al, %al
+; KNL-NEXT:    setne %al
+; KNL-NEXT:    vzeroupper
+; KNL-NEXT:    retq
+;
+; SKX-LABEL: allzeros_v8f32_nnan:
+; SKX:       # %bb.0:
+; SKX-NEXT:    vxorps %xmm1, %xmm1, %xmm1
+; SKX-NEXT:    vcmpneqps %ymm1, %ymm0, %k0
+; SKX-NEXT:    kortestb %k0, %k0
+; SKX-NEXT:    setne %al
+; SKX-NEXT:    vzeroupper
+; SKX-NEXT:    retq
+  %1 = fcmp nnan une <8 x float> %a0, zeroinitializer
+  %2 = bitcast <8 x i1> %1 to i8
+  %3 = icmp ne i8 %2, 0
+  ret i1 %3
+}
+
 ; The below are IR patterns that should directly represent the behavior of a
 ; MOVMSK instruction.